Changing the plan in Hostgator
 

I have a blog for which I have hostgator Hatchling plan for single domain hosting. Now I want to host another domain on hostgator by upgrading subscribed plan. But the hosting provider is telling that you can't upgrade the plan. They are suggesting me to subscribe new multi domain plan. By subscribing new plan I have to manually restore my site. Is there any other way to do this? Without any manual work.